The invention relates to a rotary piston engine having at least two rotary pistons, both being formed as gearwheels mounted in a rotatable fashion on mutually perpendicular axes in a housing providing a closed seal for the pistons on both faces as well as around their circumferences, and being at one point in a sliding, mutually sealing engagement of gear teeth with each other.
Reference is made to DE 33 17 089 A1, DE 33 17 330 C2, DE 27 31 534 C3, DE 33 21 461 C2, DT 2 104 595, DE 26 55 649 A1, DT 2 034 300, DE 260 704, EP 0 091 975 A1 as well as DE 227 054 and GB 17,535 with general regard to the prior art.
Most of these already disclosed proposals are based on a design having two meshing piston rings, the axes of which intersect in the middle of the piston ring, as a result of which the two piston rings have the same midpoint, or alternatively a design having two piston rings, the pistons of which are only formed on the outer surface of the ring. In embodiments in which a piston ring rotates in the inner chamber of a second piston ring, although the spherical sealing surfaces are the same for both piston rings, the sealing in direction of rotation is not ensured in one of two points of intersection. Sealing in the direction of rotation is also not ensured in the second of the aforementioned embodiments; further disadvantages are also presented by the dimensions and weight of such an engine.
All of the already disclosed solutions are based on the familiar system of the carburetion of a combustible mixture followed by a subsequent combustion process. Resulting disadvantageously from the design of the system, there is a very short time available for carburetion of the combustible mixture and its subsequent combustion. Additional disadvantages arise from the valve timing control systems usually required.
Disadvantages are presented by an incomplete combustion of fuel and the associated generation of harmful exhaust gases. For the purpose of extending the time available for carburetion and combustion of the fuel mixture, the air and fuel are often mixed in a carburetor, i.e. a long distance ahead of the combustion chamber, or, in the case of fuel injection systems, in the intake port.
The solutions disclosed thus far have favored the use of the largest possible size of combustion chamber, which does however incur disadvantages resulting from the design of the system. The present invention is therefore based on the assumption that very low capacity engines offer the best efficiency ratios and enable better conditions for combustion to be achieved.
The object of the present invention was therefore to develop a rotary piston engine displaying the advantages of a very low capacity engine, i.e. enabling near-complete fuel combustion and minimizing emissions of harmful exhaust gases.
Based on the rotary piston engine described above, this object is achieved, according to the invention, by means of the following features:
a) the at least two rotary pistons have different diameters;
b) the internal teeth and external teeth of the at least two rotary pistons contact at an angle of 45xc2x0 in each case and have slightly helical flanks;
c) tooth spaces, forming a carburetion chamber, a compression chamber and a working chamber, have an inside contour precisely matching the shape of the teeth;
d) each of the internal teeth and external teeth of the at least two rotary pistons is assigned each of throughflow bores, wherein the latter forming a combustion chamber and being incorporated in the rotary piston, wherein said each of the throughflow bores opens into an outlet on the circular surface areas of the at least two rotary pistons which lie opposite to each other, wherein a closed seal being provided through certain angles of rotation for the bore at points opposing to housing walls which enclose one of the at least two rotary pistons in a sandwich arrangement;
e) ahead of the point in a sliding, mutually sealing engagement of gear teeth, lies a first connecting duct for each of the at least two rotary pistons in the aforementioned housing walls. This duct provides a flow connection between the tooth space rotating past it and a throughflow bore and filles the latter with compressed air or a fuel mixture;
f) behind the point in a sliding, mutually sealing engagement of gear teeth, lies a second connecting duct for each of the at least two rotary pistons in the aforementioned housing walls, wherein the second connecting duct provides a flow connection between the throughflow bores rotating past the second connecting duct and one of the subsequent tooth spaces, into which the charge in said each of the throughflow bores expands;
g) the aforementioned housing walls incorporate exhaust opening both before and after the point in a sliding, mutually sealing engagement of gear teeth as well as intake openings lying opposite to the exhaust openings, wherein the intake openings are connected to an air intake or a fuel mixture intake, wherein the intake openings are flow-connected in sequence to the tooth spaces passing by.
According to the invention, therefore, the carburetion process is isolated in time and space from the standard processes encountered in conventional internal combustion engines in that a separate xe2x80x9ccarburetion cyclexe2x80x9d is created. This is achieved by an arrangement of sequentially operating combustion chambers in a rotary piston. During a compression cycle in a tooth space the compressed medium is pressed into a combustion chamber which is also incorporated in the rotary piston and subsequently remains closed for the aforementioned xe2x80x9ccarburetion cyclexe2x80x9d. The pressure required for the subsequent work cycle is generated by the forward combustion chamber in the rotary piston, in which the entire carburetion process and the combustion process have just been completed. The combustion chambers incorporated in the rotary piston are linked in sequence via ducts formed in the engine housing to working volumes formed by the tooth spaces.
According to the invention, a large number of very small combustion chambers are therefore created, and at the same time sufficient time and space is provided for carburetion and combustion of the combustible mixture. This improves the energy yield and reduces emissions of harmful pollutants. In terms of design, it is also advantageous that the rotary piston engine according to the invention does not require a crankshaft, connecting rods or valves.
Any type of fuel is suitable for operation of the rotary piston engine according to the invention, in particular hydrogen or alcohol, or fuel mixtures, such as naphtha with water. Here it is advantageous if the throughflow bores forming the combustion chambers are equipped with catalysts or inserts for flameless combustion. When using hydrogen, water injection can be utilized, whereas a nickel insert is suitable for a naphtha/water mixture.
The rotary piston engine according to the invention is not only suitable for use in airplane engines, ship engines and automotive engines, but also in electricity generators.
For formation of the individual cycle sequences it is useful if the intake opening overlaps the opposing exhaust opening for a partial angle of rotation. It is also advantageous if the intake opening extends across an angular width of more than one tooth space.
In order to extend the service life, it is advantageous if the throughflow bores forming the combustion chambers and possibly also the secondary connecting ducts are coated with a layer of heat insulating material.
Further advantages of the invention are explained in greater detail by means of an exemplary embodiment.